Most people grow up with a strong sense of what upsets other people. And you can bet that if some action upsets people, there will be a law about it. Sometimes the law is that the upsetting action is legal. Black people drinking from a "white" water fountain used to be illegal in 1950, but now it's perfectly legal, even if some bigots are upset about it. But most times, if a large number of people would upset by an action, then that action is illegal.
If you want to know what's legal and what's not, just consult your conscience and ask yourself if most people would be upset or outraged by your actions. Try to put yourself in the other person's place. That will cover 99% of the situations, for the rest, just obey the traffic signs, and pay attention to what happens to other people. There a few special cases where you will need to consult an expert ... such as if you want to open a daycare center ... but even for those, common sense should tell you that you need to consult that expert.
Sadly, a lot of people seem to be lacking common sense about the law, and empathy for other peoples feelings. When you add moral blindness to that mix, you get a dangerous person.